Oracle 11g Release 2

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WITH yourTable AS (
   SELECT 'xa220' AS UNIQUE_ID, 1 AS ID, 'John Smith' AS NAME, 'Berlin' AS CITY, date '2020-05-01' AS "DATE" FROM dual UNION ALL
   SELECT 'xa195', 1, 'John Smith',  'Berlin',   date '2020-03-01' FROM dual UNION ALL
   SELECT 'xa111', 1, 'John Smith',  'München',  date '2020-01-01' FROM dual UNION ALL
   SELECT 'xa106', 2, 'James Brown', 'Atlanta',  date '2018-04-04' FROM dual UNION ALL
   SELECT 'xa100', 2, 'James Brown', 'Boston',   date '2017-12-10' FROM dual UNION ALL
   SELECT 'xa76',  3, 'Emily Wolf',  'Shanghai', date '2016-11-03' FROM dual UNION ALL
   SELECT 'xa20',  3, 'Emily Wolf',  'Shanghai', date '2016-07-03' FROM dual UNION ALL
   SELECT 'xa15',  3, 'Emily Wolf',  'Tokyo',    date '2014-02-22' FROM dual UNION ALL
   SELECT 'xa12',  3, 'Emily Wolf',  NULL,       date '2014-02-22' FROM dual
),
cte AS (
    SELECT t.*, LAG(CITY, 1, CITY) OVER (PARTITION BY ID ORDER BY "DATE") LAG_CITY
    FROM yourTable t
)

SELECT ID, NAME, CITY, LAG_CITY AS PREVIOUS_CITY
FROM cte
WHERE CITY <> LAG_CITY OR CITY IS NULL AND LAG_CITY IS NOT NULL OR CITY IS NOT NULL AND LAG_CITY IS NULL
ORDER BY ID, "DATE" DESC;

ID	NAME	CITY	PREVIOUS_CITY
1	John Smith	Berlin	München
2	James Brown	Atlanta	Boston
3	Emily Wolf	Shanghai	Tokyo
3	Emily Wolf	Tokyo	null